Summary of findings 9. Vitamin K antagonists versus active control.
| VKA compared with aspirin for primary thromboprophylaxis in ambulatory cancer patients receiving chemotherapy | |||||||
|
Patient or population: ambulatory cancer patients receiving chemotherapy Settings: outpatient clinics Intervention: VKA Comparison: aspirin | |||||||
| Outcomes | Relative effect (95% CI) | Illustrative comparative risks* (95% CI) | Differenceb (95% CI) | No of participants (studies) | Certainty of the evidence (GRADE) | What it means | |
| Assumed riska | Corresponding risk | ||||||
|
With aspirin Number of events per 1000 participants |
With VKA Number of events per 1000 participants |
||||||
|
Symptomatic VTE Follow‐up: median 2.1 years |
RR 1.50 (0.74 to 3.04) | Intermediate‐risk populationc | 27 per 1000 more events (14 fewer to 211 more) | 440 (1) | ⊕⊕⊕⊝ Moderated | VKA probably increases the incidence of symptomatic VTE when compared to aspirin in multiple myeloma. | |
| 55 per 1000 | 82 per 1000 (40 to 166) | ||||||
|
Major bleeding Follow‐up: median 2.1 years |
RR 0.14 (0.01 to 2.75) | Intermediate‐risk populationc | 12 per 1000 fewer events (14 fewer to 24 more) | 440 (1) | ⊕⊕⊝⊝ Lowe | VKA may reduce the incidence of major bleeding when compared to aspirin in multiple myeloma. | |
| 14 per 1000 | 2 per 1000 (0 to 38) | ||||||
|
Symptomatic PE Follow‐up: median 2.1 years |
RR 1.00 (0.25 to 3.95) | Intermediate‐risk populationc | 0 per 1000 fewer events (14 fewer to 54 more) | 440 (1) | ⊕⊕⊕⊝ Moderated | VKA is probably as effective as aspirin in the prevention of symptomatic PE in multiple myeloma. | |
| 18 per 1000 | 18 per 1000 (5 to 72) | ||||||
|
Symptomatic DVT Follow‐up: median 2.1 years |
RR 1.75 (0.75 to 4.09) | Intermediate‐risk populationc | 27 per 1000 more events (9 fewer to 112 more) | 440 (1) | ⊕⊕⊕⊝ Moderated | VKA probably increases the incidence of symptomatic DVT when compared to aspirin in multiple myeloma. | |
| 36 per 1000 | 64 per 1000 (27 to 149) | ||||||
|
Any VTE Follow‐up: NA |
NAf | Intermediate‐risk populationc | NA | NA | NA | We do not know how VKA affects any VTE when compared to aspirin across different cancer types. | |
| NA | NA | ||||||
|
1‐year overall mortality Follow‐up: NA |
NAf | Intermediate‐risk populationc | NA | NA | NA | We do not know how VKA affects 1‐year overall mortality when compared to aspirin across different cancer types. | |
| NA | NA | ||||||
|
Clinically relevant bleeding Follow‐up: NA |
NAf | Intermediate‐risk populationc | NA | NA | NA | We do not know how VKA affects clinically relevant bleeding when compared to aspirin across different cancer types. | |
| NA | NA | ||||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; DVT: deep vein thrombosis; NA: not applicable; PE: pulmonary embolism; RR: risk ratio; VKA: vitamin K antagonists; VTE: venous thromboembolism. | |||||||
|
GRADE Working Group grades of evidence High certainty: further research is very unlikely to change our confidence in the estimate of effect. Moderate certainty: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low certainty: further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low certainty: we are very uncertain about the estimate. | |||||||
aThe assumed risk was calculated from the observed control group risk in Palumbo 2011. bDifference calculated as the absolute risk difference between the assumed risk and corresponding risk, expressed per 1000. cIntermediate‐risk population refers to the median observed risk to experience symptomatic VTE in the trials contributing to the analyses (55 per 1000). Rates between 2% and 7% are considered intermediate risk (Khorana 2008). dDowngraded one level because of imprecision. Although attrition bias may have occurred, it is unlikely to have changed the results in a clinically relevant manner. eDowngraded two levels because of imprecision. Although attrition bias may have occurred, it is unlikely to have changed the results in a clinically relevant manner. fNo trials contributed to this outcome.